Series-parallel process system for preparing ethanol by hydrogenation of ethyl acetate

Abstract

A series-parallel process system for the hydrogenation of ethyl acetate to ethanol belongs to the technical field of ethyl acetate hydrogenation to ethanol production. The system comprises multiple subsystems connected in series or parallel. In each subsystem, the tube-side outlet of the feed heat exchanger is connected to the inlet of the vaporizer, and its outlet pipe is connected to the inlet of the reactor. The reactor outlet is connected to the shell-side inlet of the feed heat exchanger, and the shell-side outlet is connected to the separator. In this system, ethyl acetate enters the multi-stage reactors in parallel, while hydrogen and recirculation gas enter the multi-stage reactors in series. With the same hydrogen-to-ester ratio, the recirculation gas volume is reduced by more than half, significantly reducing the energy consumption of the recirculation unit. Simultaneous entry of ethyl acetate into the multi-stage reactors facilitates adjustment of reactor loads and synchronized catalyst aging. If a single-stage reactor or equipment fails or requires catalyst replacement, it can be shut down individually for troubleshooting while the other stage continues operation. This system enables large-scale production capacity.

Description

Technical Field

[0001] This utility model relates to a series-parallel process system for the hydrogenation of ethyl acetate to ethanol, belonging to the technical field of hydrogenation of ethyl acetate to ethanol. Background Technology

[0002] As a major energy consumer, my country urgently needs to find alternatives to gasoline due to its energy structure of abundant coal, scarce oil, and limited natural gas. Ethanol, as a clean energy source, has excellent miscibility and can be blended into gasoline as a component, partially replacing it and increasing its octane rating and oxygen content. This effectively promotes complete combustion and reduces carbon oxide emissions from vehicle exhaust. As a partial substitute for vehicle fuel, ethanol can diversify the structure of my country's vehicle fuel supply.

[0003] Currently, my country mainly uses grain, especially corn, as raw material to develop fuel ethanol. However, there are many unfavorable factors in using grain as raw material for ethanol production. Starting from coal resources, producing ethanol from syngas has broad market prospects.

[0004] Ethanol production using syngas as a feedstock has been industrialized, with mainstream processes including hydrogenation of methyl acetate to ethanol, hydrogenation of ethyl acetate to ethanol, and direct hydrogenation of acetic acid to ethanol. Among these, several units of the hydrogenation of ethyl acetate to ethanol process are already in operation. The main process route is to produce acetic acid from methanol, esterify acetic acid to produce ethyl acetate, and then hydrogenate ethyl acetate to produce ethanol.

[0005] Based on current production processes and hydrogenation catalysts, a high hydrogen-to-ester ratio is required for the hydrogenation reaction to improve the conversion rate of ethyl acetate. In large-scale plants, this ratio is approximately 30-50, necessitating a large volume of circulating hydrogen to meet production needs. This results in high energy consumption of the circulating unit and high production costs. Therefore, providing a low-volume, energy-efficient method for the hydrogenation of ethyl acetate to ethanol has become a pressing issue for those skilled in the art. Utility Model Content

[0006] To address the problems existing in the prior art, this utility model provides a series-parallel process system for the hydrogenation of ethyl acetate to produce ethanol, which has the advantages of low gas circulation volume, reduced energy consumption, good reaction effect, and flexible operation.

[0007] This utility model is achieved through the following technical solution: a series-parallel process system for the hydrogenation of ethyl acetate to ethanol, wherein the raw material hydrogen and the circulating gas are combined and enter the inlet of the tube side of the first-stage feed heat exchanger; the tube side outlet of the first-stage feed heat exchanger is connected to the inlet of the first-stage vaporizer after passing through the first heater; the outlet pipeline of the first-stage vaporizer is connected to the inlet of the first-stage reactor after passing through the second heater; the outlet of the first-stage reactor is connected to the shell side inlet of the first-stage feed heat exchanger; the shell side outlet of the first-stage feed heat exchanger is connected to the first-stage separator; and the gas phase outlet of the first-stage separator is connected to the tube side inlet of the second-stage feed heat exchanger.

[0008] The tube-side outlet of the secondary feed heat exchanger is connected to the inlet of the secondary vaporizer via the third heater. The outlet pipe of the secondary vaporizer is connected to the inlet of the secondary reactor via the fourth heater. The outlet of the secondary reactor is connected to the shell-side inlet of the secondary feed heat exchanger. The shell-side outlet of the secondary feed heat exchanger is connected to the secondary separator. The gas phase outlet of the secondary separator is connected to the circulator. The outlet pipe of the circulator is connected to the inlet pipe of the hydrogen feedstock.

[0009] The raw material pipe for ethyl acetate is connected to the inlet of the primary vaporizer and the secondary vaporizer, respectively.

[0010] Furthermore, the liquid phase outlets of the primary separator and the secondary separator are connected to the crude product separation and purification unit.

[0011] Furthermore, the system is also equipped with a primary system outlet backup pipeline and a secondary system inlet backup pipeline. The primary system outlet backup pipeline is a pipeline that directly connects the gas phase outlet of the primary separator to the inlet of the circulating machine. The secondary system inlet backup pipeline is a pipeline that directly connects the hydrogen feedstock inlet pipe to the inlet of the primary separator.

[0012] Furthermore, both the primary reactor and the secondary reactor are adiabatic reactors.

[0013] The beneficial effects of this invention are as follows: In this system, ethyl acetate enters the first and second stage reactors in parallel, while hydrogen and circulating gas enter the first and second stage reactors in series. Under the same hydrogen-ester ratio, the circulating gas volume is reduced by half, and the energy consumption of the circulating machine is greatly reduced.

[0014] Ethyl acetate is introduced into both the first and second stage reactors simultaneously, which facilitates the adjustment of the reactor loads and allows for synchronized catalyst aging. If a single-stage reactor or equipment fails, or the catalyst needs replacement, it can be shut down separately to address the problem; the other stage system continues to operate. This enables large-scale production capacity. Attached Figure Description

[0015] Figure 1 Flowchart of the process for hydrogenating ethyl acetate to ethanol.

[0016] In the diagram: E-2001, primary feed and discharge heat exchanger; E-2002, first heater; E-2003, second heater; E-2004, secondary feed and discharge heat exchanger; E-2005, third heater; E-2006, fourth heater; D-2001, primary vaporizer; D-2002, secondary vaporizer; D-2003, primary separator; D-2004, secondary separator; C-2001, circulating machine; R-2001, primary reactor; R-2002, secondary reactor. Detailed Implementation

[0017] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention, but are not limited thereto, unless otherwise stated.

[0018] Figure 1 A series-parallel process system for the hydrogenation of ethyl acetate to ethanol is shown, in which ethyl acetate is split into two streams and enters a two-stage vaporizer.

[0019] After the raw hydrogen and circulating gas are combined, they pass through the tube side of the primary feed heat exchanger E-2001. The gas after heat exchange is heated by heater E-2002 and then enters the primary vaporizer D-2001 to mix with ethyl acetate sprayed into the vaporizer. The mixed gas is then heated by the second heater E-2003 and enters the primary reactor R-2001. The gas after reaction passes through the shell-side inlet of the primary feed heat exchanger E-2001 and enters the primary separator D-2003. The liquid phase is collected, and the gas phase passes through the secondary feed heat exchanger E-2001. In the tube side (04), the gas after heat exchange is heated by the third heater (E-2005) and then enters the secondary vaporizer (D-2002) to mix with the ethyl acetate sprayed into the vaporizer. The mixed gas is then heated by the fourth heater (E-2006) and enters the secondary reactor (R-2002). The gas after reaction passes through the shell side of the secondary feed heat exchanger (E-2004) and then enters the secondary separator (D-2004). Most of the gas phase at the outlet of the secondary separator (D-2004) returns to the recycle machine (C-2001), a small portion goes to the PSA for hydrogen extraction, and the liquid phase is collected.

[0020] The liquid phase collected from the primary separator D-2003 and the secondary separator D-2004 enters the crude product separation and purification unit.

[0021] If a single-stage reactor or equipment malfunctions or the catalyst needs replacement, it can be shut down individually to address the problem; the other stage system continues to operate. When the standby gas outlet line of the primary system is activated, the gas phase outlet of the primary separator D-2003 is directly connected to the inlet line of the recirculating unit C-2001. This means the gas phase from the primary separator D-2003 can directly return to the recirculating unit C-2001, shutting down the secondary reaction system, with only the primary reaction system operating. When the standby gas inlet line of the secondary system is activated, the hydrogen feedstock inlet is directly connected to the inlet of the primary separator D-2003. This means the hydrogen, after merging with the recirculated gas, can directly enter the secondary feed-discharge heat exchanger E-2004, directly into the secondary reaction system.

[0022] Ethyl acetate is fed into the first and second stage reactors in parallel, while hydrogen and circulating gas are fed into the first and second stage reactors in series. Under the same hydrogen-to-ester ratio, the circulating gas volume is reduced by half, and the energy consumption of the circulating machine is significantly reduced.

[0023] The above embodiments are only used to illustrate the present utility model. Any equivalent transformations and improvements made on the basis of the technical solution of the present utility model shall not be excluded from the protection scope of the present utility model.

Claims

1. A series-parallel process system for the hydrogenation of ethyl acetate to ethanol, characterized in that: After the raw hydrogen and the circulating gas merge, they enter the inlet of the tube side of the first-stage feed heat exchanger (E-2001). The tube side outlet of the first-stage feed heat exchanger (E-2001) is connected to the inlet of the first-stage vaporizer (D-2001) via the first heater (E-2002). The outlet pipe of the first-stage vaporizer (D-2001) is connected to the inlet of the first-stage reactor (R-2001) via the second heater (E-2003). The outlet of the first-stage reactor (R-2001) is connected to the shell side inlet of the first-stage feed heat exchanger (E-2001). The shell side outlet of the first-stage feed heat exchanger (E-2001) is connected to the first-stage separator (D-2003). The gas phase outlet of the first-stage separator (D-2003) is connected to the tube side inlet of the second-stage feed heat exchanger (E-2004). The tube-side outlet of the secondary feed heat exchanger (E-2004) is connected to the inlet of the secondary vaporizer (D-2002) via the third heater (E-2005). The outlet pipe of the secondary vaporizer (D-2002) is connected to the inlet of the secondary reactor (R-2002) via the fourth heater (E-2006). The outlet of the secondary reactor (R-2002) is connected to the shell-side inlet of the secondary feed heat exchanger (E-2004). The shell-side outlet of the secondary feed heat exchanger (E-2004) is connected to the secondary separator (D-2004). The gas phase outlet of the secondary separator (D-2004) is connected to the recirculator (C-2001). The outlet pipe of the recirculator (C-2001) is connected to the inlet pipe of the hydrogen feedstock. The raw material pipe for ethyl acetate is connected to the inlet of the primary vaporizer (D-2001) and the secondary vaporizer (D-2002), respectively.

2. The series-parallel process system for the hydrogenation of ethyl acetate to ethanol according to claim 1, characterized in that: The liquid phase outlets of the primary separator (D-2003) and the secondary separator (D-2004) are connected to the crude product separation and purification unit.

3. The series-parallel process system for the hydrogenation of ethyl acetate to ethanol according to claim 1, characterized in that: The system is also equipped with a primary system outlet backup pipeline and a secondary system inlet backup pipeline. The primary system outlet backup pipeline is a pipeline that directly connects the gas phase outlet of the primary separator (D-2003) to the inlet of the circulating machine (C-2001). The secondary system inlet backup pipeline is a pipeline that directly connects the hydrogen feedstock inlet pipe to the inlet of the primary separator (D-2003).

4. The series-parallel process system for the hydrogenation of ethyl acetate to ethanol according to claim 1, characterized in that: Both the primary reactor (R-2001) and the secondary reactor (R-2002) are adiabatic reactors.

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